The invention is directed toward a drive shaft coupling including a rotational range of “free-motion” for interconnecting a driving component and a driven component.
In many instances, a driving component is required to be operably interconnected with a driven component for driving communication. Further, the interconnection must enable a degree of relative motion between the driving and the driven components. For example, in many agricultural operations a tractor is used to tow a secondary agricultural implement. Also, the tractor operably drives the secondary agricultural implement. To achieve this, the tractor typically includes an output shaft (i.e. a driving component) operably interconnected to an input shaft (i.e. driven component) of the secondary agricultural implement. The interconnection is typically achieved by a drive shaft disposed between the components.
In almost all instances, the tractor is used for a variety of tasks. Accordingly, various types of secondary agricultural implements must be readily engageable with the tractor. Thus, connection and disconnection of the drive shaft assembly is required. Often, the output shaft of the tractor and the input shaft of the secondary agricultural implement are not sufficiently aligned and thus prohibit quick interconnection therebetween. Thus, it is desirable to provide a drive shaft assembly that includes a range of rotational motion, or “free-motion” to enable interconnection between the input and output shafts when they are out of exact rotational alignment.
To this end, it is known in the art to provide a telescoping drive shaft assembly including a rotational range of “free-motion” along the telescopic interconnection. Such a drive shaft assembly is illustrated in U.S. Pat. Nos. 5,827,122 and 5,938,534, assigned to Neapco, Inc. The patents each provide a drive shaft assembly, which includes telescopically interconnectable first and second drive shaft halves. The telescopic interconnection further includes a tooth/groove arrangement. The arrangement enables a range of relative rotation between the first and second halves. Also, the arrangement concurrently provides relative axial motion.
The prior art methods detailed above retain certain disadvantages. Specifically, the telescoping interconnection of the drive shaft assembly preferably includes first and second shafts each having a lemon-shaped cross-section including a generally circular shape with diametrically opposed extended portions or ribs. In this manner, the ribs fix the first and second shafts for common rotation while enabling relative axial plunging. Such a cross-section, while preferable due to reduced manufacturing costs, is unable to properly function when including a “free-motion” function. A further disadvantage of the prior art methods is that the possibility does not exist to separate the telescoping and rotational functions. Such separation may be desirable for particular applications.